“From chaos, Lord, I came alive, My thirst to chaos goes And, of repose once born, I
strive To go back to repose!” Hyperion, you out of chasm Arise with worlds of grace! Ask
not for wonder or phantasm That has no name or face…”
Mihai Eminescu From the poem “Luceafarul”

What lies at the bottom of Hyperion’s strange craters?
Nobody knows. To help find out, the robot Cassini spacecraft now orbiting Saturn swooped past
the sponge-textured moon again and took an image of unprecedented detail. That image, shown
above, shows a remarkable world strewn with strange craters and a generally odd surface. The
slight differences in colour possibly show differences in surface composition. At the bottom
of most craters lies some type of unknown dark material. Inspection of the image shows bright
features indicating that the dark material might be only tens of metres thick in some places.
Hyperion is about 250 kilometres across, rotates chaotically, and has a density so low that it
might house a vast system of caverns inside.Cassini Imaging Team, SSI, JPL,
ESA, NASA.

When is a moon not a moon?

Earth has a second moon, of sorts, and could have many others, according to three astronomers
who did calculations to describe orbital motions at gravitational points in space, that
temporarily pull asteroids into bizarre orbits near our planet. The 3-mile-wide (5-km)
satellite, which takes 770 years to complete a horseshoe-shaped orbit around Earth, is called
Cruithne and will remain in a suspended state around Earth for at least 5,000 years.

The finding is based on work by 18th century French mathematician Joseph-Louis Lagrange, whose
name is given to the five points of equilibrium that occur between the gravitational forces of
planets and the sun. (As illustrated in the last edition of “What’s Up”).

Cruithne approaches the Earth, and when it gets close enough, it turns around and retreats,
only to repeat its performance on the other side. This unusual arrangement, in which close
encounters with a planet do not result in impacts or strong distortion of the asteroids orbit
is termed a ‘horseshoe’ orbit because of its shape. The asteroid doesn’t
really go around the Earth, but rather shares the Earth’s orbit with it. (Another way to
think of this horseshoe is to consider a three-lane, circular race track. The Earth is a large
truck moving at a constant speed down the centre lane and the asteroid is a car. When in the
outer lane, the car is going a bit slower than the truck, and the truck starts to catch up.
But just when the truck is about to pass, the car switches to the inner lane and speeds up. It
then starts to pull away from the truck, but because the track is circular, the car will
eventually catch up with the truck from behind. When it gets close, the car again switches to
the outer lane and slows down. Then the whole cycle repeats. This is what is happening in a
simple horseshoe. Both vehicles share the same highway, but in a co-ordinated fashion so as to
avoid collision. In reality, the delicate co-ordination of the asteroid and the Earth is
performed by the laws of celestial mechanics, and requires just the right conditions.)

Cruithne was first discovered in 1986, but scientists working at Queen Mary and Westfield
College in London were intrigued enough with its wanderings to develop mathematical models to
describe its path. That led them to suggest that ‘co-orbital dynamics’ could
explain the movement of other objects captured at the Lagrangian points. “We found new
dynamical channels through which free asteroids become temporarily moons of Earth and stay
there from a few thousand years to several tens of thousands of years. Eventually these same
channels provide the moons with escape routes. So the main difference between the moon
(we’ve always known) and the new moons is that the latter are temporary --they come and
go, but they stay for a very long time before they leave.” said Fathi Namouni, one of
the researchers, now at Princeton University.

Astronomers have become very aware of the large numbers of asteroids that inhabit the solar
system. Most orbit the sun in a belt between Mars and Jupiter, but a handful cross
Earth’s orbit.

Cruithne takes 770 years to complete its horseshoe orbit. Every 385
years, it comes to its closest point to Earth, some 9.3 million miles (15 million kilometres)
away. Its next close approach to Earth comes in 2285. Cruithne’s orbit is exceedingly
strange. “With respect to the Earth it moves very slowly,” said Namouni’s
colleague Apostolos Christou. “At specific points in its orbit, it reverses its rate of
motion with respect to Earth so it will appear to go back and forth.”

What is a moon?

Namouni and his colleagues believe that co-orbital motions probably describe the orbits of
many objects at the Lagrange points, but are these objects moons? A moon is usually defined as
an object whose orbit encompasses a planet rather than the sun.

In the view of Carl Murray, who worked with Namouni and Christou on the research, there are
three classes of moons -large moons in near-circular orbits around a planet, that formed soon
after the planet; smaller fragments that are the products of collisions; and outer, irregular
moons in odd orbits, or captured asteroids like Cruithne. In the past year, astronomers have
reported finding such objects around Uranus.

So where does our ‘real’ moon fit into this classification, given that scientists
think it is the result of a Mars-sized object slamming against our planet soon after it
formed? Murray speculates that our own moon is in many ways unique and its formation seems
like a one-off event.

There are almost certainly more temporary moons of Earth and other planets, waiting to be
discovered. As scientists get better at discovering asteroids, they will find more that have
orbits that will keep them close to Earth for a long period of time. But some of those objects
are very small. We are beginning to redefine our understanding both of ‘planets’
and ‘moons’.

Namouni does not think of Cruithne as a real ‘moon’ because it moves around the
Earth at this time but may not forever. Earth is causing Cruithnes present trajectory, but it
could eventually escape.

So its not a true moon of Earth, but it might become one. The researchers found that Cruithne
is likely to use the new dynamical channels to become a real moon of the Earth and remain so
for 3,000 years. Their finding throws into question the current official counts of moons
around the planets, since there may be dozens of unknown asteroids circling each planet in
temporary or permanent orbits due to gravitational balance points.

For now, Namouni believes there should be a new category of moons -temporary moons that are
captured for a few thousand to several tens of thousands of years.

Dave Ogden
(Compiled from several www sources)

Stephen Baxter

The strange asteroid Cruithne, described above, figures largely in a novel written by one of
our forthcoming speakers. The novel, “Time” by Stephen Baxter, relates a
mysterious series of events in which the asteroid is of primary importance. Stephen will be
speaking to us in the new year.

Stephen Baxter was born in Liverpool in 1957. He is a trained engineer with degrees from
Cambridge (mathematics) and Southampton Universities (doctorate in aero engineering research).
He worked as a teacher of mathematics and physics, and for several years in information
technology. In 1991 he applied to become a cosmonaut, aiming for the spot on Mir eventually
taken by Helen Sharman. Stephen has been a full time author since 1995.

He is the author of over 30 books, all published in the US and UK, and several in Germany,
Japan, France, and other countries. His novel “Voyage” was dramatised by for BBC
Radio in 1999. His TV and movie work includes development work on the BBC’s
“Invasion Earth” and the script for the Episode 3 of “Space Island
One”, broadcast on Sky One in January 1998. His non-fiction includes the books Deep
Future and Omegatropic.

He has won many awards for his novels. Several of his short stories have won prizes, including
the “Writers of the Future” contest. He is a lifetime supporter of Liverpool FC.

Astronomers have discovered (as reported in one of our recent workshops) that Pluto may have
not one, but three moons, which will make it the first body in the Kuiper Belt known to have
more than one satellite. The candidate moons, provisionally designated S/2005 P1 and S/2005
P2, are approximately 27,000 miles away from Pluto --in other words, two to three times as far
from Pluto as Charon. They are tiny, with estimated diameters between 40 and 125 miles.
Charon, for comparison, is about 730 miles in diameter, while Pluto itself has a diameter of
about 1410 miles. The team plans to make follow-up Hubble observations in February to confirm
that the newly discovered objects are truly Pluto’s moons. Only after confirmation will
the International Astronomical Union consider permanent names for the objects.

The Hubble telescope’s ‘advanced camera for surveys’ observed the two new
candidate moons on May 15. Three days later, Hubble looked at Pluto again. The two objects
were still there and appeared to be moving in orbit around Pluto. A re-examination of older
Hubble images taken on 2002 June 14 has confirmed the presence of both P1 and P2 near the
predicted locations based on the 2005 Hubble observations. The team looked long and hard but
unsuccessfully for other potential moons around Pluto.

Astronomers using the Keck II telescope report the discovery of a second satellite of the
transneptunian object 2003 EL61. The satellite is more than four magnitudes fainter than the
primary and appears to have a circular orbit with a 34.1-day period. 2003 EL61 is the
third-brightest Kuiper-belt object, after Pluto and 2005 FY9. About 10% of Kuiper-belt objects
have satellites, but until recently no other object in the Kuiper belt was known to have more
than one.

NASA has published plans for the next generation of spacecraft to take people back to the Moon
and on to Mars and other destinations. The study makes specific design recommendations for a
vehicle to carry crews into space, a family of launch vehicles to take them to the Moon and
beyond, and a ‘lunar mission architecture’ for landing on the Moon. It also
recommends the technologies that NASA should pursue in the near term. The study will assist
NASA in achieving President Bush’s ‘vision for space exploration’, which
calls for the agency to return the space shuttle to safe flight, complete the International
Space Station, return to the Moon, and continue exploration to Mars and beyond.

America’s next-generation spacecraft will use an improved, blunt-body crew capsule, and
will accommodate up to six people. The spacecraft will be built upon the foundation of the
proven designs and technologies used in the Apollo and space shuttle programmes, while having
far greater capability. It will be able to carry larger and heavier cargoes into space and
allow more people to stay on the Moon for longer periods of time. The new spacecraft will be
able to be configured either to support human explorers or fly unpiloted to carry cargo. Its
design allows the flexibility to ferry crews of three astronauts, plus additional supplies, to
and from the International Space Station, take four crew members to lunar orbit, and
eventually maintain up to six astronauts on a mission to Mars. Crews and cargo will be carried
into orbit by a launcher consisting of a solid-propellant booster and an upper stage powered
by a Shuttle main engine that can lift 25 metric tons. The spacecraft is intended to be safer
than the space shuttle because of its in-line design and launch-abort system.

Images returned during Cassini’s recent fly-by of Titan show evidence of what appears to
be a shoreline cutting across the southern hemisphere, dividing a distinct bright and dark
region roughly 1,700 kilometres long by 170 kilometres wide. Next to an area that is bright
and possibly rough is one that is very dark and smooth. Patterns in the dark area indicate
that it may once have been flooded with liquid that may now have partially receded. Bay-like
features also lead scientists to speculate that the bright--dark boundary is most likely a
shoreline.

The Andromeda galaxy is thought to have at its core a super-massive black hole that the Hubble
telescope now finds to be surrounded by a disc of young stars. The newly discovered disc is
composed of over 400 very hot, young blue stars, orbiting like a planetary system very close
to the black hole. That puzzles astronomers because the black hole’s intense
gravitational field should have torn apart any clouds of matter long before they could
coalesce to form new stars. The stars form a very flat disc that is only one light-year
across. An elliptical disc of older red stars surrounds it, spanning about five light-years.
Since the two discs appear to be in the same plane, they are probably related, but no one
understands how either disc came into being. Spectroscopic observations made by Hubble suggest
that the disc of blue stars is only about 200 million years old, while the Galaxy itself is
far older. They also allowed astronomers to determine the movement of the blue stars and
thereby estimate the black hole’s mass. It really IS super-massive, with a mass 140
million times that of our Sun.

A team of astronomers using the VLT has discovered a large population of distant galaxies
observed when the Universe was only 10 to 30 per cent of its present age. A total sample of
about 8,000 galaxies selected only on the basis of their observed brightness in red light was
found to include almost 1,000 bright and vigorously star-forming galaxies that were formed
between 9 and 12 billion years ago, i.e. about 1,500 to 4,500 million years after the Big
Bang. The galaxies had been missed because previous surveys had selected objects in a much
more restrictive manner. While observations and models had previously indicated that the
Universe had not yet formed many stars in the first billion years of cosmic time, the
discovery calls for a significant revision, since it now seems that stars formed two to three
times more quickly than some astronomers had thought.

The European Space Agency is planning a mission to see how well current technology could
deal with the threat of an asteroid impact. For a rehearsal deflection mission, dubbed Don
Quixote, the agency has selected asteroids 2002 AT4 and (10302) 1989 ML as possible mission
targets, but the final decision will be made when the launch date has been fixed. The mission
will see two spacecraft travel to the chosen asteroid. The first, called Sancho, will arrive
several months in advance of the second, Hidalgo. When Hidalgo arrives to smash into the
asteroid, Sancho will be there to observe any changes to the asteroid’s orbit.

Astronomers have discovered that one of the most distant galaxies ever seen is unusually
massive and mature. The galaxy, named HUDF-JD2, appears to have built up amazingly quickly,
within the first few hundred million years after the Big Bang. It put about eight times more
mass into stars than there is in our own Milky Way today, and then, just as suddenly, it
stopped forming new stars. The galaxy was identified among approximately 10,000 others in a
small patch of sky called the Hubble Ultra Deep Field. It represents an era when the Universe
was only 800 million years old, about five per cent of its present age. Scientists studying
the Ultra Deep Field found the galaxy in Hubble’s infrared images. They expected it to
be young and small, like other known galaxies at similar distances. Instead, they found
evidence that the galaxy is remarkably mature and much more massive. Its stars appear to have
been in place for a long time. Moreover the galaxy looks even brighter in longer-wavelength
infrared images from the Spitzer space telescope. Spitzer is sensitive to the light from
older, redder stars, which should make up most of the mass in a galaxy. The infrared
brightness of the galaxy suggests that it was already comparable in mass to present-day large
galaxies.

European Space Agency member states have approved funding for the ExoMars mission --a key
milestone in the Aurora programme, ESA’s vision to send spacecraft and eventually
astronauts to the Moon and Mars. In the near term, it focuses on robotic missions --ExoMars in
2011, followed by an international Mars sample-return mission. Science minister Lord Sainsbury
said that, as a major contributor, the UK will have a leading role in the programme, which
should improve our understanding of Mars and the Solar System. The bulk of the money will be
used to develop ExoMars, with the rest being used for basic research into future missions to
the Moon and Mars. The UK is contributing £73m out of a total subscription of around
£508m. That should give British industry a considerable share of the work, perhaps
allowing it to regain confidence lost as a result of the ill-fated Beagle 2 mission.

The Mars Express spacecraft, which has been orbiting, Mars since 2003 has been granted a
mission extension of one Martian year (nearly two Earth years). Mars Express has helped to
give us a more complete view of the planet, including evidence for atmospheric methane, a
frozen sea and ‘geological’ activity. But one of its instruments may now have
stopped working, and deployment of its radar was delayed for a year. The Marsis (Mars Advanced
Radar for Subsurface and Ionosphere Sounding) was finally deployed in the middle of this year
after fears that one or both of its 20m-long booms might hit the spacecraft after opening out.
The mission extension should allow Marsis to restart its search for water reservoirs beneath
the planet’s surface. Other instruments have been measuring the composition and
characteristics of the Martian surface and atmosphere, and have suggested that volcanic and
glacial processes have occurred much more recently than had been supposed.

The twin Mars rovers have successfully explored the surface of the planet for a full
Martian year (687 Earth days). The rovers’ original mission was scheduled for only three
months. Both rovers keep finding new variations of bedrock in the areas that they are
exploring on opposite sides of Mars. The geological information that they have collected
suggests that ancient Martian environments included periods of wet conditions. Aided by a
power supply from batteries charged by Spirit’s solar cells, researchers have been using
one of the rovers at night for astronomical observations. One experiment watched the sky
during a meteor shower as Mars passed through the debris trail left by a passage of
Halley’s comet.

The Earth’s north magnetic pole is drifting away from North America and toward
Siberia at such a speed that Alaska might lose its spectacular Northern Lights in the
foreseeable future. In spite of accelerated movement over the past century, the possibility
that Earth’s modestly fading magnetic field will collapse is remote, but the shift could
mean that aurorae might become more visible in more southerly areas of Siberia and Europe. The
magnetic poles mark the axis of the magnetic field generated by liquid iron in the
Earth’s core and are far from coinciding with the geographical poles. Scientists have
long known that the magnetic poles migrate, and that at long intervals they exchange places,
although why they do so is unknown. Previous studies have shown that the strength of the field
has decreased by 10% over the past 150 years; during the same period, the north magnetic pole
has wandered about 685 miles out into the Arctic. The rate of movement has increased in the
last century in comparison with the fairly steady movement of the previous four centuries.

Observations of Comet 9P/Tempel 1 made by the Rosetta spacecraft after the Deep Impact
collision suggest that, if Tempel 1 is at all typical, comets are ‘icy dirtballs’
rather than ‘dirty snowballs’ as previously believed. In July this year, the Deep
Impact mission sent an impactor probe to hit Tempel 1. The collision was expected to excavate
a crater with a diameter of about 100-125 metres and to eject cometary material. It vaporised
4500 tons of water, but surprised the investigators by releasing even more dust. At a distance
of about 80 million kilometres from the comet, Rosetta observed before and after the impact
and measured the water vapour content and the cross-section of the dust created by the impact.
The scientists could then work out the corresponding dust/ice mass ratio, which is larger than
one, so it looks as if Tempel 1 is composed more of dust held together by ice, rather than
made of ice contaminated with dust. The scientists did not find evidence of enhanced outburst
activity of Tempel 1 in the days after the impact, suggesting that impacts of meteoroids are
not the cause of cometary outbursts, at least in the case of Tempel 1.

The Japan Aerospace Exploration Agency (JAXA) has reported that a miniature robot, released by
the Japanese space probe Hayabusa in the course of its investigation of the small asteroid
Itokawa, was lost before it was able to land on the asteroid’s surface. Itokawa, a
600m-long asteroid that travels in an orbit that takes it between the Earth and Mars, is named
after Hideo Itokawa, the father of Japan’s space exploration programme. It is currently
around 290 million km away from the Earth. Hayabusa, which was launched on 2003 May 9, has
been hovering over Itokawa for almost two months. Minerva, a 10-cm-long can-shaped robot, was
designed to gather information on Itokawa as part of a rehearsal for Hayabusa’s own
landing, scheduled for November 19.

Minerva’s landing was to have been the first attempt by Japan to send
information-gathering equipment to an extra-terrestrial object. Equipped with a camera and
thermometers, Minerva was meant to hop around Itokawa and send data such as surface
temperatures and images back to Earth via Hayabusa. A previous attempt to land Minerva earlier
this month was aborted owing to technical problems.

The Spitzer telescope has detected for the first time the building blocks of planets
around brown dwarfs, suggesting that such failed stars probably operate the same
planet-building process as proper stars are supposed to do. There are tiny crystals and dust
grains circling five brown dwarfs located 520 light years away in the constellation
Chamaeleon. The crystals, composed of a green mineral commonly found on Earth and known as
olivine, are thought to be the building blocks of planets.

Scientists using the Spitzer space telescope say that they have detected light that may be
from the earliest objects in the Universe. A 10-hour observation of an area in the
constellation Draco by Spitzer’s infrared array camera showed a diffuse glow that may be
from Population III stars, a hypothesised class of stars thought to have formed before all
others. Theorists say that some of the first stars may have been over a hundred times as
massive as the Sun and extremely hot, bright, and short-lived, each lasting only a few million
years. The ultraviolet light that they emitted would by now have been shifted into the
infrared by the Universe’s expansion. The Spitzer observation confirms a result from the
Cosmic Background Explorer satellite in the 1990s that suggested that there might be an
infrared background that could not be attributed to known stars. It also supports a 2003
estimate, made by users of the Wilkinson Microwave Anisotropy Probe, that stars first ignited
200--400 million years after the Big Bang.

An international team of astronomers has used the Hubble Space Telescope to observe the
spectrum of the white dwarf Sirius B. The new results allow the white dwarf’s mass to be
determined from the red shift caused in the spectrum by its intense gravitational field.
Scattered light from the very bright Sirius A, only a few seconds of arc away, has presented
great difficulties for Earth-based observers. Sirius B has a diameter of 7,500 miles, less
than the size of the Earth, but it is enormously dense. Its gravitational field is 350,000
times greater than ours. The new measurements show that Sirius B has a mass that is 98% of
that the Sun; Sirius itself has a mass twice that of the Sun and a diameter of 1.5 million
miles.

When fact and fiction meet

The concept of cheaper and more easily accessible space flight is another interesting feature
of the Stephen Baxter novel “Time” mentioned earlier in this issue. In the novel,
a maverick “privateer” launches a cheap and cheerful space probe from the Mojave
desert towards the asteroid Cruithne. The following article may ring some bells for those who
have read the novel.

Virgin Galactic and the New Mexico Spaceport

Leonard David -Space.com
The first purpose-built commercial spaceport for the personal space
flight industry is to be constructed in New Mexico, a deal struck between the state and Virgin
Galactic, the private spaceline firm created by British billionaire, Sir Richard Branson.
Details of the partnership were unveiled this month in a Santa Fe, New Mexico gathering of
state officials led by Governor Bill Richardson, spaceport planning officials, and leaders of
Virgin Galactic, including Branson. Richardson announced that he will work with the state
legislature to secure a three year commitment for a total of $100 million for the
state’s share of the funding to build the world’s first commercial spaceport to be
built in southern New Mexico. The Governor’s funding package will be the cornerstone of
a larger $225 million financial construction package that includes local, state and federal
funding to build New Mexico’s spaceport in Upham, New Mexico. In announcing the
partnership, Richardson emphasised that New Mexico wants to be on the ground floor of public
space travel. He said that today’s announcement will “change the face of the state
and change the face of the world.” Calling it a very simple, but highly significant
agreement, Richardson explained that the state of New Mexico “will build the first
spaceport and Virgin Galactic will locate their mission and headquarters right here in New
Mexico.” “I would be interested in being the first New Mexican, flying the first
time out of the New Mexico spaceport,” Richardson said in a post-announcement press
briefing. Rick Homans, New Mexico Spaceport Authority Chairman and New Mexico Economic
Development Department Secretary said that construction of the spaceport will begin as early
as 2007 and be completed by 2009 or 2010.

To boldly go.....

Branson explained that with the historic partnership, “New Mexico will be known around
the world as the launch pad of the new space industry.” He said that within a few years
“…we intend to take two to three flights a day to space from New Mexico.”
“We’re going where no one has gone before. There’s no model to follow,
nothing to copy. That is what makes this so exciting,” Branson explained. “We
might even be able to allow those aliens who landed at Roswell 50 years ago in a UFO a chance
to go home.” Will Whitehorn, president of Virgin Galactic, said that his company
believes the future of space doesn’t lie in just ground-based rocketry. Rather,
air-launched spaceships are the way to establish safe, affordable, mass transportation into
space. Whitehorn said that it has taken governments four decades to get 500 people to space.
“We hope to do that in year one…and eventually be carrying up to 10,000 people a
year by the later years of the project,” he said.

Environmentally-friendly spaceport

Prior to commercial space treks from New Mexico, Whitehorn said that Mojave, California is the
site for an extensive test program of some 50 to 60 flights of SpaceShipTwo. That craft is now
under development by aerospace designer, Burt Rutan and his team at Scaled Composites based in
Mojave, California. Current conceptual views of the spaceport, Whitehorn said, are tied to
making it “the most environmentally-friendly spaceport/airport type structure
that’s been built.” Largely to be fabricated underground, the New Mexico
spaceport, for example, would use solar energy and an advanced water collection system.
Spotlighting the natural beauty of New Mexico, Whitehorn said that spaceport facilities will
be underground as much as possible, “actually hidden from the ground, but visible when
you’re in space and coming back to the Earth.” Present at the spaceport
announcement was movie actress Victoria Principal. She has already purchased a $200,000 Virgin
Galactic ticket. “I am thrilled about the first Virgin Galactic civilian flight
scheduled for 2008 and I look forward to being on it,” Principal told the audience.
“We’re on an era of a new form of transportation and a way of life that
we’ve never known before,” she said.

Five spaceship systems are on order

In a statement from Rutan’s Scaled Composites today, the group congratulated Virgin and
New Mexico on their spaceport plans. On October 4, 2004, Rutan’s SpaceShipOne rocketed
into history, becoming the first private piloted spacecraft to exceed an altitude of 62 miles
(100 kilometres) twice in as many weeks, thus claiming the X Prize Foundation’s $10
million dollar Ansari X Prize. SpaceShipOne’s development was bankrolled by
Microsoft’s co-founder, Paul Allen. In July, Branson and Rutan announced their
signing of an agreement to form The Spaceship Company to build a fleet of commercial
suborbital spaceships and launch aircraft. Under license from Paul Allen’s Mojave
Aerospace Company, The Spaceship Company will adopt the “care-free reentry”
concept and the “cantilevered-hybrid” rocket motor technology developed for the
Ansari X Prize-winning SpaceShipOne. Scaled’s development work on the commercial
suborbital spaceliner design will be performed in its current Mojave, California facilities.
The Spaceship Company production is also planned to take place at the Mojave Spaceport. The
Scaled statement today noted that Virgin Galactic has ordered five spaceship systems and has
options on more. Following delivery of the Virgin Galactic ships, The Spaceship Company
“will supply flight hardware to additional commercial spaceline operators.”

Thanks to all who contributed to this edition. If you have contributions for future
editions, please send them, if possibe, by email to dogden<AT>ntlworld<DOT>com
Dave Ogden.

The array of colourful stars in this South facing view is well worth studying. From east to
west, Regulus in Leo is a spectral type B star. Saturn appears slightly higher as a yellowish
colour. Next, with spectral type F, comes pale yellow Procyon, 8th brigtest star in the sky.
Lower to the west, and unmistakably the brighest and whitest, at mag -2.1, is Sirius a type A
star. Betelgeuse is a red M supergiant star. Its brightness varies from 0.4 mag to 1.3 mag
with no set period. During pulsations the diameter varies from 300 to 400 times the diameter
of the sun. Rigel, a blue-white B type giant of 0.08 mag is sixth brightest star in the sky.
Aldebaran is an orange K type giant star, with a diameter about forty times the Sun's.
Finally for comparison is the clear orange glow of Planet Mars. All colours will be more
apparent when viewed through a pair of binoculars, e.g. 10x50. Try defocussing the image.